Primary intermediates for oxidative coloration of hair

ABSTRACT

Primary intermediates for hair coloring compositions for oxidative dyeing of hair are compounds of the formula (1):  
                 
 
     where R 1 , and R 2  are each individually selected from a hydrogen atom, a C 1  to C 3  alkyl group, a C 1  to C 5  mono or dihydroxyalkyl group; phenyl or benzyl optionally substituted with an alkoxy group, or R 1  and R 2  together with the nitrogen atom to which they are attached form a piperazine, piperidine, imidazole, or morpholine ring.

FIELD OF THE INVENTION

[0001] This invention relates to new 2-substituted 4-amino-phenol derivative compounds and compositions containing these compounds, as primary intermediates for oxidative coloring of hair fibers.

BACKGROUND OF THE INVENTION

[0002] Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the method most extensively to color hair is an oxidative dyeing process utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.

[0003] Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.

[0004] A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, N,N-bis(2-hydroxyethyl)-p- phenylene diamine, 1-(2-hydroxyethyl)-4,5-diaminopyrazole and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, 2,4-diaminophenoxyethanol, and 5-amino-2-methylphenol.

[0005] There are numerous additional requirements for oxidation dye compounds that are used to dye human hair besides the color or the desired intensity. Thus, the dye compounds must be unobjectionable in regard to toxicological and dermatological properties and must provide the desired hair color with a good light fastness, fastness to a permanent wave treatment, acid fastness and fastness to rubbing. The color of the hair dyed with the dye compounds in each case must be stable for at least 4 to 6 weeks to light, rubbing and chemical agents. Furthermore, an additional requirement is the production of a broad palette of different color shades using different developer and coupler substances. Many of the desired shades have been produced with dyes based on p-aminophenol. However, as indicated in U.S. Pat. No. 4,997,451, the use of p-aminophenol is being questioned for possible toxicological reasons. The proposed replacements for p-aminophenol have not proved entirely satisfactory. There is therefore a need for new primary intermediate compounds to meet one or more of the desired properties but not possessing the possible toxicological drawbacks possessed by p-aminophenol.

SUMMARY OF THE INVENTION

[0006] It is therefore an object of this invention to provide new primary intermediate compounds useful in place of p-aminophenol to provide a wide range of different color shades with various combinations of primary intermediates and couplers, but which avoids the drawbacks of p-aminophenol.

[0007] It has been discovered that new certain 2-substituted 4-amino-phenol derivative compounds are suitable primary intermediates for hair coloring compositions and systems for providing good oxidative coloration of hair and for providing acceptable light fastness, good selectivity, fastness to shampooing, fastness to perspiration and permanent wave treatment, and suitable for providing a wide variety of different color shades with various primary intermediate and coupler compounds.

[0008] The invention provides new compounds of Formula (1):

[0009] wherein R₁ and R₂ are each individually selected from hydrogen atoms, C₁ to C₅ alkyl, C₁ to C₅ mono or dihydroxyalkyl, phenyl or benzyl optionally substituted with a hydroxyl, amino or C₁ to C₃ alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are attached form a C₃ to C₆, preferably C₄ to C₆, saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms.

[0010] These novel primary intermediates are used to provide coloration to hair in which there is good dye uptake by the hair and provides shades or colors which are stable over a relatively long period of time. The novel primary intermediates provide for dyeing of hair to impart color or shades that possess good wash fastness and do not undergo significant changes on exposure to light or shampooing.

DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred 4-amino-phenol derivative compounds of this invention are those of formula (1)

[0012] wherein R₁ and R₂ are each individually selected from a hydrogen atom, a C₁ to C₃ alkyl group, preferably methyl groups; phenyl or benzyl optionally substituted with an alkoxy group, preferably a methoxy group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a piperazine, piperidine, imidazole, or morpholine ring.

[0013] Especially preferred compounds of formula (1) of this invention are the following compounds:

[0014] 4-amino-2-(1-phenylamino-ethyl)-phenol;

[0015] 4-amino-2-(1-piperidin-1-yl-ethyl)-phenol;

[0016] 4-amino-2-[1-(pyridin-3-yl-amino)-ethyl]-phenol;

[0017] 4-amino-2-(1-benzylamino-ethyl)phenol;

[0018] 4-amino-2-[1-(4-methoxy)-phenylamino-ethyl]-phenol;

[0019] 4-amino-2-(1-amino-ethyl)-phenol;

[0020] 4-amino-2-(1-dimethylamino-ethyl)-phenol;

[0021] 4-amino-2-(1-morpholin-4-yl-ethyl)-phenol;

[0022] 4-amino-2-[1-(4-methoxy)-benzylamino-ethyl]-phenol;

[0023] 4-amino-2-(1-methylamino-ethyl)-phenol; and

[0024] 4-amino-2-[1-(2-hydroxyethylamino)-ethyl]-phenol.

[0025] The new compounds of formula (1) of this invention can be prepared according to the following reaction sequence wherein R₁ and R₂ are as defined hereinbefore:

[0026] In this synthesis procedure 5-butylamido-2-hydroxyacetophenone of formula (2) is subjected to reductive amination with the reagent R₁R₂NH using reducing agents such as sodium triacetoxyborohydride, sodium cyanoborohydride or polymethylhydrosiloxane (PMHS) to produce a compound of formula (3). Hydrolysis of the compound of formula (3) with methanolic hydrochloric acid produces a compound of formula (1).

Synthesis Examples 1 to 11

[0027] Employing the appropriate R₁R₂NH reagent, reducing agent and 5-butylamido-2-hydroxyacetophenone in the synthesis procedure described, the following compounds of formula (1) of this invention can be prepared:

[0028] 4-amino-2-(1-phenylamino-ethyl)-phenol;

[0029] 4-amino-2-(1-piperidin-1-yl-ethyl)-phenol;

[0030] 4-amino-2-[1-(pyridin-3-y-amino)-ethyl]-phenol;

[0031] 4-amino-2-(1-benzylamino-ethyl)-phenol;

[0032] 4-amino-2-[1-(4-methoxy)-phenylamino-ethyl]-phenol;

[0033] 4-amino-2-(1-amino-ethyl)-phenol;

[0034] 4-amino-2-(1-dimethylamino-ethyl)-phenol;

[0035] 4-amino-2-(1-morpholin-4-yl-ethyl)-phenol;

[0036] 4-amino-2-[1-(4-methoxy)-benzylamino-ethyl]-phenol;

[0037] 4-amino-2-(1-methylamino-ethyl)-phenol; and

[0038] 4-amino-2-[1-(2-hydroxyethylamino)-ethyl]-phenol.

[0039] As used herein, the term “hair dyeing composition” (also synonymously referred to herein as the hair dye composition, the hair coloring composition, or the hair dye lotion) refers to the composition containing oxidation dyes, including the novel compounds described herein, prior to admixture with the developer composition. The term “developer composition” (also referred to as the oxidizing agent composition or the peroxide composition) refers to compositions containing an oxidizing agent prior to admixture with the hair dyeing composition. The term “hair dye product” or “hair dye system” (also referred to as the hair dyeing system, hair dyeing product, or hair coloring system) interchangeably refer to the combination of the hair dyeing composition and the developer composition before admixture, and may further include a conditioner product and instructions, such product or system often being provided packaged as a kit. The term “hair dyeing product composition” refers to the composition formed by mixing the hair dyeing composition and the developer composition. “Carrier” (or vehicle or base) refers to the combination of ingredients contained in a composition excluding the active agents (e.g., the oxidation hair dyes of the hair dyeing composition).

[0040] Hair coloring (i.e., hair dyeing) compositions of this invention can contain, in combination with oxidation dye couplers, a novel primary intermediate of this invention as the sole primary intermediate or can also contain other primary intermediates. Thus, one or more suitable primary intermediates may be used in combination with the novel primary intermediates of this invention.

[0041] Suitable known primary intermediates include, for example,

[0042] p-phenylenediamine derivatives such as: benzene-1,4-diamine (commonly known as p-phenylenediamine), 2-methyl-benzene-1,4-diamine, 2-chloro-benzene-1,4-diamine, N-phenyl-benzene-1,4-diamine, N-(2-ethoxyethyl)benzene-1,4-diamine, 2-[(4-amino-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, (commonly known as N,N-bis(2-hydroxyethyl)-p-phenylenediamine) (2,5-diamino-phenyl)-methanol, 1-(2,5-diamino-phenyl)-ethanol, 2-(2,5-diamino-phenyl)-ethanol, N-(4-aminophenyl)benzene-1,4-diamine, 2,6-dimethyl-benzene-1,4-diamine, 2-isopropyl-benzene-1,4-diamine, 1-[(4-aminophenyl)amino]-propan-2-ol, 2-propyl-benzene-1,4-diamine, 1,3-bis[(4-aminophenyl)(2-hydroxyethyl)amino]propan-2-ol, N⁴,N⁴, 2-trimethylbenzene-1,4-diamine, 2-methoxy-benzene-1,4-diamine, 1-(2,5-diaminophenyl)ethane-1,2-diol, 2,3-dimethyl-benzene-1,4-diamine, N-(4-amino-3-hydroxy-phenyl)-acetamide, 2,6-diethylbenzene-1,4-diamine, 2,5-dimethylbenzene-1,4-diamine, 2-thien-2-ylbenzene-1,4-diamine, 2-thien-3-ylbenzene-1,4-diamine, 2-pyridin-3-ylbenzene-1,4-diamine, 1,1′-biphenyl-2,5-diamine, 2-(methoxymethyl)benzene-1,4-diamine, 2-(aminomethyl)benzene-1,4-diamine, 2-(2,5-diaminophenoxy)ethanol, N-[2-(2,5-diaminophenoxy)ethyl]-acetamide, N,N-dimethylbenzene-1,4-diamine, N,N-diethylbenzene-1,4-diamine, N,N-dipropylbenzene-1,4-diamine, 2-[(4-aminophenyl)(ethyl)amino]ethanol, 2-[(4-amino-3-methyl-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, N-(2-methoxyethyl)-benzene-1,4-diamine, 3-[(4-aminophenyl)amino]propan-1-ol, 3-[(4-aminophenyl)-amino]propane-1,2-diol, N-{4-[(4-aminophenyl)amino]butyl}benzene-1,4-diamine, and 2-[2-(2-{2-[(2,5-diaminophenyl)-oxy]ethoxy}ethoxy)ethoxy]benzene-1,4-diamine;

[0043] p-aminophenol derivatives such as: 4-amino-phenol (commonly known as p-aminophenol), 4-methylamino-phenol, 4-amino-3-methyl-phenol, 4-amino-2-hydroxymethyl-phenol, 4-amino-2-methyl-phenol, 4-amino-2-[(2-hydroxy-ethylamino)-methyl]-phenol, 4-amino-2-methoxymethyl-phenol, 5-amino-2-hydroxy-benzoic acid, 1-(5-amino-2-hydroxy-phenyl)-ethane-1,2-diol, 4-amino-2-(2-hydroxy-ethyl)-phenol, 4-amino-3-(hydroxymethyl)phenol, 4-amino-3-fluoro-phenol, 4-amino-2-(aminomethyl)-phenol, and 4-amino-2-fluoro-phenol;

[0044] o-aminophenol derivatives such as: 2-amino-phenol (commonly known as o-aminophenol), 2,4-diaminophenol, 2-amino-5-methyl-phenol, 2-amino-6-methyl-phenol, N-(4-amino-3-hydroxy-phenyl)-acetamide, and 2-amino-4-methyl-phenol; and

[0045] heterocyclic derivatives such as: pyrimidine-2,4,5,6-tetramine (commonly known as 2,4,5,6-tetraaminopyridine), 1-methyl-1H-pyrazole-4,5-diamine, 2-(4,5-diamino-1H-pyrazol-1-yl)ethanol, N²,N²-dimethyl-pyridine-2,5-diamine, 2-[(3-amino-6-methoxypyridin-2-yl)amino]ethanol, 6-methoxy-N²-methyl-pyridine-2,3-diamine, 2,5,6-triaminopyrimidin-4(1H)-one, pyridine-2,5-diamine, 1-isopropyl-1H-pyrazole-4,5-diamine, 1-(4-methylbenzyl)-1H-pyrazole-4,5-diamine, 1-(benzyl)-1H-pyrazole-4,5-diamine, and 1-(4-chlorobenzyl)-1H-pyrazole-4,5-diamine.

[0046] The novel primary intermediates of formula (1) of this invention may be used with any suitable coupler(s) in hair coloring compositions or systems of this invention.

[0047] Suitable known couplers include, for example:

[0048] phenols, resorcinol and naphthol derivatives such as: naphthalene-1,7-diol, benzene-1,3-diol, 4-chlorobenzene-1,3-diol, naphthalen-1-ol, 2-methyl-naphthalen-1-ol, naphthalene-1,5-diol, naphthalene-2,7-diol, benzene-1,4-diol, 2-methyl-benzene-1,3-diol, 7-amino-4-hydroxy-naphthalene-2-sulfonic acid, 2-isopropyl-5-methyl phenol, 1,2,3,4-tetrahydro-naphthalene-1,5-diol, 2-chloro-benzene-1,3-diol, 4-hydroxy-naphthalene-1-sulfonic acid, benzene-1,2,3-triol, naphthalene-2,3-diol, 5-dichloro-2-methylbenzene-1,3-diol, 4,6-dichlorobenzene-1,3-diol, and 2,3-dihydroxy-[1,4]naphthoquinone;

[0049] m-phenylenediamines such as: 2,4-diaminophenol, benzene-1,3-diamine, 2-(2,4-diamino-phenoxy)-ethanol, 2-[(3-amino-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, 2-methyl-benzene-1,3-diamine, 2-[[2-(2,4-diamino-phenoxy)-ethyl]-(2-hydroxy-ethyl)-amino]-ethanol, 4-{3-[(2,4-diaminophenyl)oxy]propoxy}benzene-1,3-diamine, 2-(2,4-diamino-phenyl)-ethanol, 2-(3-amino-4-methoxy-phenylamino)-ethanol, 4-(2-amino-ethoxy)-benzene-1,3-diamine, (2,4-diamino-phenoxy)-acetic acid, 2-[2,4-diamino-5-(2-hydroxy-ethoxy)-phenoxy]-ethanol, 4-ethoxy-6-methyl-benzene-1,3-diamine, 2-(2,4-diamino-5-methyl-phenoxy)-ethanol, 4,6-dimethoxy-benzene-1,3-diamine, 2-[3-(2-hydroxy-ethylamino)-2-methyl-phenylamino]-ethanol, 3-(2,4-diamino-phenoxy)-propan-1-ol, N-[3-(dimethylamino)phenyl]urea, 4-methoxy-6-methylbenzene-1,3-diamine, 4-fluoro-6-methylbenzene-1,3-diamine, 2-({3-[(2-hydroxyethyl)amino]-4,6-dimethoxyphenyl}-amino)ethanol, 3-(2,4-diaminophenoxy)-propane-1,2-diol, 2-[2-amino-4-(methylamino)-phenoxy]ethanol, 2-[(5-amino-2-ethoxy-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, 2-[(3-aminophenyl)amino]ethanol, N-(2-aminoethyl)benzene-1,3-diamine, 4-{[(2,4-diamino-phenyl)oxy]methoxy}-benzene-1,3-diamine, and 2,4-dimethoxybenzene-1,3-diamine;

[0050] m-aminophenols such as: 3-amino-phenol, 2-(3-hydroxy-4-methyl-phenylamino)-acetamide, 2-(3-hydroxy-phenylamino)-acetamide, 5-amino-2-methyl-phenol, 5-(2-hydroxy-ethylamino)-2-methyl-phenol, 5-amino-2,4-dichloro-phenol, 3-amino-2-methyl-phenol, 3-amino-2-chloro-6-methyl-phenol, 5-amino-2-(2-hydroxy-ethoxy)-phenol, 2-chloro-5-(2,2,2-trifluoro-ethylamino)-phenol, 5-amino-4-chloro-2-methyl-phenol, 3-cyclopentylamino-phenol, 5-[(2-hydroxyethyl)amino]-4-methoxy-2-methylphenol, 5-amino-4-methoxy-2-methylphenol, 3-(dimethylamino)phenol, 3-(diethylamino)phenol, 5-amino-4-fluoro-2-methylphenol, 5-amino-4-ethoxy-2-methylphenol, 3-amino-2,4-dichloro-phenol, 3-[(2-methoxyethyl)amino]phenol, 3-[(2-hydroxyethyl)amino]phenol, 5-amino-2-ethyl-phenol, 5-amino-2-methoxyphenol, 5-[(3-hydroxypropyl)amino]-2-methylphenol, 3-[(3-hydroxy-2-methylphenyl)-amino]propane-1,2-diol, and 3-[(2-hydroxyethyl)amino]-2-methylphenol; and

[0051] heterocyclic derivatives such as: 3,4-dihydro-2H-1,4-benzoxazin-6-ol, 4-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, 6-methoxyquinolin-8-amine, 4-methylpyridine-2,6-diol, 2,3-dihydro-1,4-benzodioxin-5-ol, 1,3-benzodioxol-5-ol, 2-(1,3-benzodioxol-5-ylamino)ethanol, 3,4-dimethylpyridine-2,6-diol, 5-chloropyridine-2,3-diol, 2,6-dimethoxypyridine-3,5-diamine, 1,3-benzodioxol-5-amine, 2-{[3,5-diamino-6-(2-hydroxy-ethoxy)-pyridin-2-yl]oxy}-ethanol, 1H-indol-4-ol, 5-amino-2 ,6-dimethoxypyridin-3-ol, 1H-indole-5,6-diol, 1H-indol-7-ol, 1H-indol-5-ol, 1H-indol-6-ol, 6-bromo-1,3-benzodioxol-5-ol, 2-aminopyridin-3-ol, pyridine-2,6-diamine, 3-[(3,5-diaminopyridin-2-yl)oxy]propane-1,2-diol, 5-[(3,5-diaminopyridin-2-yl)oxy]pentane-1,3-diol, 1H-indole-2,3-dione, indoline-5,6-diol, 3,5-dimethoxypyridine-2,6-diamine, 6-methoxypyridine-2,3-diamine, and 3,4-dihydro-2H-1,4-benzoxazin-6-amine.

[0052] Preferred primary intermediates include:

[0053] p-phenylenediamine derivatives such as: 2-methyl-benzene-1,4-diamine, benzene-1,4-diamine, 1-(2,5-diamino-phenyl)-ethanol, 2-(2,5-diamino-phenyl)-ethanol, N-(2-methoxyethyl)benzene-1,4-diamine, 2-[(4-amino-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, and 1-(2,5-diaminophenyl)ethane-1,2-diol;

[0054] p-aminophenol derivatives such as 4-amino-phenol, 4-methylamino-phenol, 4-amino-3-methyl-phenol, 4-amino-2-methoxymethyl-phenol, and 1-(5-amino-2-hydroxy-phenyl)-ethane-1,2-diol;

[0055] o-aminophenol derivatives such as: 2-amino-phenol, 2-amino-5-methyl-phenol, 2-amino-6-methyl-phenol, N-(4-amino-3-hydroxy-phenyl)-acetamide, and 2-amino-4-methyl-phenol; and

[0056] heterocyclic derivatives such as: pyrimidine-2,4,5,6-tetramine, 1-methyl-1H-pyrazole-4,5-diamine, 2-(4,5-diamino-1H-pyrazol-1-yl)ethanol, 1-(4-methylbenzyl)-1H-pyrazole-4,5-diamine, 1-(benzyl)-1H-pyrazole-4,5-diamine, and N²,N²-dimethyl-pyridine-2,5-diamine.

[0057] Preferred couplers include:

[0058] phenols, resorcinol and naphthol derivatives such as: naphthalene-1,7-diol, benzene-1,3-diol, 4-chlorobenzene-1,3-diol, naphthalen-1-ol, 2-methyl-naphthalen-1-ol, naphthalene-1,5-diol, naphthalene-2,7-diol, benzene-1,4-diol, 2-methyl-benzene-1,3-diol, and 2-isopropyl-5-methylphenol;

[0059] m-phenylenediamines such as: benzene-1,3-diamine, 2-(2,4-diamino-phenoxy)-ethanol, 4-{3-[(2,4-diaminophenyl)oxy]propoxy}benzene-1,3-diamine, 2-(3-amino-4-methoxy-phenylamino)-ethanol, 2-[2,4-diamino-5-(2-hydroxy-ethoxy)-phenoxy]-ethanol, and 3-(2,4-diamino-phenoxy)-propan-1-ol;

[0060] m-aminophenols such as: 3-amino-phenol, 5-amino-2-methyl-phenol, 5-(2-hydroxy-ethylamino)-2-methyl-phenol, and 3-amino-2-methyl-phenol; and

[0061] heterocyclic derivatives such as: 3,4-dihydro-2H-1,4-benzoxazin-6-ol, 4-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, 1,3-benzodioxol-5-ol, 1,3-benzodioxol-5-amine, 1H-indol-4-ol, 1H-indole-5,6-diol, 1H-indol-7-ol, I H-indol-5-ol, 1H-indol-6-ol, 1H-indole-2,3-dione, pyridine-2,6-diamine, and 2-aminopyridin-3-ol.

[0062] Most preferred primary intermediates include:

[0063] p-phenylenediamine derivatives such as: 2-methyl-benzene-1,4-diamine, benzene-1,4-diamine, 2-(2,5-diamino-phenyl)-ethanol, 1-(2,5-diamino-phenyl)-ethanol, and 2-[(4-amino-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol;

[0064] p-aminophenol derivatives such as: 4-amino-phenol, 4-methylamino-phenol, 4-amino-3-methyl-phenol, and 1-(5-amino-2-hydroxy-phenyl)-ethane-1,2-diol;

[0065] o-aminophenols such as: 2-amino-phenol, 2-amino-5-methyl-phenol, 2-amino-6-methyl-phenol, and N-(4-amino-3-hydroxy-phenyl)-acetamide; and

[0066] heterocyclic derivatives such as: pyrimidine-2,4,5,6-tetramine, 2-(4,5-diamino-1H-pyrazol-1-yl)ethanol, 1-(4-methylbenzyl)-1H-pyrazole-4,5-diamine, and 1-(benzyl)-1H-pyrazole-4,5-diamine.

[0067] Most preferred couplers include:

[0068] phenols, resorcinol and naphthol derivatives such as: benzene-1,3-diol, 4-chlorobenzene-1,3-diol, naphthalen-1-ol, 2-methyl-naphthalen-1-ol, and 2-methyl-benzene-1,3-diol;

[0069] m-phenylenediamine such as: 2-(2,4-diamino-phenoxy)-ethanol, 2-(3-amino-4-methoxy-phenylamino)-ethanol, 2-[2,4-diamino-5-(2-hydroxy-ethoxy)-phenoxy]-ethanol, and 3-(2,4-diamino-phenoxy)-propan-1-ol;

[0070] m-aminophenols such as: 3-amino-phenol, 5-amino-2-methyl-phenol, 5-(2-hydroxy-ethylamino)-2-methyl-phenol, and 3-amino-2-methyl-phenol; and

[0071] heterocyclic derivatives such as: 3,4-dihydro-2H-1,4-benzoxazin-6-ol, 4-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, 1H-indol-6-ol, and 2-aminopyridin-3-ol.

[0072] Understandably, the coupler compounds and the primary intermediate compounds, including the novel compounds of the invention, in so far as they are bases, can be used as free bases or in the form of their physiologically compatible salts with organic or inorganic acids, such as hydrochloric, citric, acetic, tartaric, or sulfuric acids, or, in so far as they have aromatic OH groups, in the form of their salts with bases, such as alkali phenolates.

[0073] The total amount of dye precursors (e.g., primary intermediate and coupler compounds, including the novel compounds of this invention) in the hair dyeing compositions of this invention is generally from about 0.002 to about 20, preferably from about 0.04 to about 10, and most preferably from about 0.1 to about 7.0 weight percent, based on the total weight of the hair dyeing composition. The primary intermediate and coupler compounds are generally used in molar equivalent amounts. However, it is possible to use the primary intermediate compounds in either excess or deficiency, i.e., a molar ratio of primary intermediate to coupler generally ranging from about 5:1 to about 1:5.

[0074] The hair dyeing compositions of this invention will contain the primary intermediate of this invention in an effective dyeing amount, generally in an amount of from about 0.001 to about 10 weight percent by weight of the hair dye composition, preferably from about 0.01 to about 5.0 weight percent. Other primary intermediates, when present, are typically present in an amount such that in aggregate the concentration of primary intermediates in the composition is from about 0.002 to about 10 weight percent, preferably from about 0.01 to about 5.0 weight percent. The coupler(s) are present in an effective dyeing concentration, generally an amount of from about 0.001 to about 10.0 weight percent by weight of the hair dye composition, preferably from about 0.01 to about 5.0 weight percent. The remainder of the hair dye composition comprises a carrier or vehicle for the couplers and primary intermediates, and comprises various adjuvants as described below.

[0075] Any suitable carrier or vehicle, generally an aqueous or hydroalcoholic solution, can be employed, preferably an aqueous solution. The carrier or vehicle will generally comprise more than 80 weight percent of the hair dye composition, typically 90 to 99 weight percent, preferably 94 to 99 weight percent. The hair coloring compositions of this invention may contain as adjuvants one or more cationic, anionic, amphoteric, or zwitterionic surface active agents, perfumes, antioxidants such as ascorbic acid, thioglycolic acid or sodium sulfite, chelating and sequestering agents such as EDTA, thickening agents, alkalizing or acidifying agents, solvents, diluents, inerts, dispersing agents, penetrating agents, defoamers, enzymes, and other dye agents (e.g., synthetic direct and natural dyes). These adjuvants are cosmetic additive ingredients commonly used in compositions for coloring hair.

[0076] The hair dye compositions of the present invention are used by admixing them with a suitable oxidant, which reacts with the hair dye precursors to develop the hair dye. Any suitable oxidizing agent can be employed in the hair dye product compositions of this invention, particularly hydrogen peroxide (H₂O₂) or precursors therefor. Also suitable are urea peroxide, the alkali metal salts of persulfate, perborate, and percarbonate, especially the sodium salt, and melamine peroxide. The oxidant is usually provided in an aqueous composition generally referred to as the developer composition, which normally is provided as a separate component of the finished hair dye product and present in a separate container. The developer composition may also contain, to the extent compatible, various ingredients needed to form the developer composition, i.e., peroxide stabilizers, foam formers, etc., and may incorporate one or more of the adjuvants referred to above, e.g., surface active agents, thickeners, pH modifiers, etc. Upon mixing the hair coloring composition and the developer composition to form a hair dye product composition, the adjuvants are provided in the hair dye product composition as it is applied to the hair to achieve desired product attributes, e.g., pH, viscosity, rheology, etc.

[0077] The form of the hair dye product compositions according to the invention can be, for example, a solution, especially an aqueous or aqueous-alcoholic solution. However, the form that is particularly preferred is a thick liquid, cream, gel or an emulsion whose composition is a mixture of the dye ingredients with the conventional cosmetic additive ingredients suitable for the particular preparation.

[0078] Suitable conventional cosmetic additive ingredients useful in the hair dye and developer compositions, and hence in the hair dye product compositions of this invention are described below, and may be used to obtain desired characteristics of the hair dye, developer and hair dye product compositions.

[0079] Solvents: In addition to water, solvents that can be used are lower alkanols (e.g., ethanol, propanol, isopropanol, benzyl alcohol); polyols (e.g., carbitols, propylene glycol, hexylene glycol, glycerin). See WO 98/27941 (section on diluents) incorporated by reference. See also U.S. Pat. No. 6,027,538 incorporated by reference. Under suitable processing, higher alcohols, such as C8 to C18 fatty alcohols, especially cetyl alcohol, are suitable organic solvents, provided they are first liquified by melting, typically at low temperature (50 to 80° C.), before incorporation of other, usually lipophilic, materials.

[0080] The organic solvents are typically present in the hair dye compositions in an amount of from about 5 to about 30% by weight of the hair dye composition. Water is usually present in an amount of from about 5 to about 90% by weight of the hair dye composition, preferably from about 15 to about 75% by weight and most preferably from about 30 to about 65% by weight.

[0081] Surfactants: These materials are from the classes of anionic, cationic, amphoteric (including zwitterionic surfactants) or nonionic surfactant compounds. (Cationic surfactants, generally included as hair conditioning materials, are considered separately below.) Suitable surfactants, other than cationic surfactants, include fatty alcohol sulfates, ethoxylated fatty alcohol sulfates, alkylsulfonates, alkylbenzensulfonates, alkyltrimethylammonium salts, alkylbetaines, ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated alkylphenols, block polymers of ethylene and/or propylene glycol, glycerol esters, phosphate esters, fatty acid alkanol amides and ethoxylated fatty acid esters, alkyl sulfates, ethoxylated alkyl sulfates, alkyl glyceryl ether sulfonates, methyl acyl taurates, acyl isethionates, alkyl ethoxy carboxylates, fatty acid mono- and diethanolamides. Especially useful are sodium and ammonium alkyl sulfates, sodium and ammonium ether sulfates having 1 to 3 ethylene oxide groups, and nonionic surfactants sold as Tergitols, e.g., C11-C15 Pareth-9, and Neodols, e.g., C12-C15 Pareth-3. They are included for various reasons, e.g., to assist in thickening, for forming emulsions, to help in wetting hair during application of the hair dye product composition, etc. Amphoteric surfactants include, for example, the asparagine derivatives as well betaines, sultaines, glycinates and propionates having an alkyl or alkylamido group of from about 10 to about 20 carbon atoms. Typical amphoteric surfactants suitable for use in this invention include lauryl betaine, lauroamphoglycinate, lauroamphopropionate, lauryl sultaine, myristamidopropyl betaine, myristyl betaine, stearoamphopropylsulfonate, cocamidoethyl betaine, cocamidopropyl betaine, cocoamphoglycinate, cocoamphocarboxypropionate, cocoa mphocarboxyg lycinate, cocobetaine, and cocoamphopropionate. Reference is made to WO 98/52523 published Nov. 26, 1998 and WO 01/62221 published Aug. 30, 2001, both incorporated herein by reference thereto.

[0082] The amount of surfactants in the hair dye compositions is normally from about 0.1% to 30% by weight, preferably 1% to 15% by weight.

[0083] Thickeners: Suitable thickeners include such as higher fatty alcohols, starches, cellulose derivatives, petrolatum, paraffin oil, fatty acids and anionic and nonionic polymeric thickeners based on polyacrylic and polyurethane polymers. Examples are hydroxyethyl cellulose, hydroxymethylcellulose and other cellulose derivatives, hydrophobically modified anionic polymers and nonionic polymers, particularly such polymers having both hydrophilic and hydrophobic moieties (i.e., amphiphilic polymers). Useful nonionic polymers include polyurethane derivatives such as PEG-150/stearyl alcohol/SDMI copolymer. Suitable polyether urethanes are Aculyn® 22, 44 and Aculyn® 46 polymers sold by Rohm & Haas. Other useful amphiphilic polymers are disclosed in U.S. Pat. No. 6,010,541 incorporated by reference. See also WO 01/62221 mentioned above. Examples of anionic polymers that can be used as thickeners are acrylates copolymer, acrylates/ceteth-20 methacrylates copolymer, acrylates/ceteth-20 itaconate copolymer, and acrylates/beheneth-25 acrylates copolymers. In the case of the associative type of thickeners, e.g., Aculyns 22, 44 and 46, the polymer may be included in one of either the hair dye composition or the developer composition of the hair dye product and the surfactant material in the another. Thus, upon mixing of the hair dye and developer compositions, the requisite viscosity is obtained. The thickeners are provided in an amount to provide a suitably thick product as it is applied to the hair. Such products generally have a viscosity of from 1000 to 100000 cps, and often have a thixotropic rheology.

[0084] pH Modifying agents: Suitable materials that are used to adjust pH of the hair dye compositions include alkalizers such alkali metal and ammonium hydroxides and carbonates, especially sodium hydroxide and ammonium carbonate, ammonia, organic amines including methylethanolamine, aminomethylpropanol, mono-, di-, and triethanolamine, and acidulents such as inorganic and inorganic acids, for example phosphoric acid, acetic acid, ascorbic acid, citric acid or tartaric acid, hydrochloric acid, etc. See U.S. Pat. No. 6,027,538 incorporated by reference.

[0085] Conditioners: Suitable materials include silicones and silicone derivatives; hydrocarbon oils; monomeric quaternary compounds, and quaternized polymers. Monomeric quaternary compounds are typically cationic compounds, but may also include betaines and other amphoteric and zwitterionic materials that provide a conditioning effect. Suitable monomeric quaternary compounds include behentrialkonium chloride, behentrimonium chloride, benzalkonium bromide or chloride, benzyl triethyl ammonium chloride, bis-hydroxyethyl tallowmonium chloride, C12-18 dialkyldimonium chloride, cetalkonium chloride, ceteartrimonium bromide and chloride, cetrimonium bromide, chloride and methosulfate, cetylpyridonium chloride, cocamidoproypl ethyldimonium ethosulfate, cocamidopropyl ethosulfate, coco-ethyldimonium ethosulfate, cocotrimonium chloride and ethosulfate, dibehenyl dimonium chloride, dicetyldimonium chloride, dicocodimonium chloride, dilauryl dimonium chloride, disoydimonium chloride, ditallowdimonium chloride, hydrogenated tallow trimonium chloride, hydroxyethyl cetyl dimonium chloride, myristalkonium chloride, olealkonium chloride, soyethomonium ethosulfate, soytrimonium chloride, stearalkonium chloride, and many other compounds. See WO 98/27941 incorporated by reference. Quaternized polymers are typically cationic polymers, but may also include amphoteric and zwitterionic polymers. Useful polymers are exemplified by polyquaternium-4, polyquaternium-6, polyquaternium-7, polyquaternium-8, polyquaternium-9, polyquaternium-10, polyquaternium-22, polyquaternium-32, polyquaternium-39, polyquaternium-44 and polyquaternium-47. Silicones suitable to condition hair are dimethicone, amodimethicone, dimethicone copolyol and dimethiconol. See also WO 99/34770 published Jul. 15, 1999, incorporated by reference, for suitable silicones. Suitable hydrocarbon oils would include mineral oil.

[0086] Conditioners are usually present in the hair dye composition in an amount of from about 0.01 to about 5% by weight of the composition.

[0087] Direct Dyes: The hair dyeing compositions according to the invention can also contain compatible direct dyes including Disperse Black 9, HC Yellow 2, HC Yellow 4, HC Yellow 15, 4-nitro-o-phenylenediamine, 2-amino-6-chloro-4-nitrophenol, HC Red 3, Disperse Violet 1, HC Blue 2, Disperse Blue 3, and Disperse Blue 377. These direct dyes can be contained in the hair coloring compositions of the invention in an amount of from about 0.05 to 4.0 percent by weight.

[0088] Natural ingredients: For example, proteins and protein derivatives, and plant materials such as aloe, chamomile and henna extracts.

[0089] Other adjuvants include polysaccharides, alkylpolyglycosides, buffers, chelating and sequestrant agents, antioxidants, and peroxide stabilizing agents as mentioned in WO 01/62221, etc.

[0090] The adjuvants referred to above but not specifically identified that are suitable are listed in the International Cosmetics Ingredient Dictionary and Handbook, (Eighth Edition) published by The Cosmetics, Toiletry, and Fragrance Association, incorporated by reference. In particular reference is made to Volume 2, Section 3 (Chemical Classes) and Section 4 (Functions) are useful in identifying a specific adjuvant to achieve a particular purpose or multipurpose.

[0091] The above-mentioned conventional cosmetic ingredients are used in amounts suitable for their functional purposes. For example, the surfactants used as wetting agents, associative agents, and emulsifiers are generally present in concentrations of from about 0.1 to 30 percent by weight, the thickeners are useful in an amount of from about 0.1 to 25 percent by weight, and the hair care functional materials are typically used in concentrations of from about 0.01 to 5.0 percent by weight.

[0092] The hair dyeing product composition as it is applied to the hair, i.e., after mixing the hair dye composition according to the invention and the developer, can be weakly acidic, neutral or alkaline according to their composition. The hair dye compositions can have pH values of from about 6 to 11.5, preferably from about 6.8 to about 10, and especially from about 8 to about 10. The pH of the developer composition is typically acidic, and generally the pH is from about 2.5 to about 6.5, usually about 3 to 5. The pH of the hair dye and developer compositions is adjusted using a pH modifier as mentioned above.

[0093] In order to use the hair coloring composition for dyeing hair, the above-described hair coloring compositions according to the invention are mixed with an oxidizing agent immediately prior to use and a sufficient amount of the mixture is applied to the hair, according to the hair abundance, generally from about 60 to 200 grams. Some of the adjuvants listed above (e.g., thickeners, conditioners, etc.) can be provided in the dye composition or the developer, or both, depending on the nature of the ingredients, possible interactions, etc., as is well known in the art.

[0094] Typically, hydrogen peroxide, or its addition compounds with urea, melamine, sodium borate or sodium carbonate, can be used in the form of a 3 to 12 percent, preferably 6 percent, aqueous solution as the oxidizing agent for developing the hair dye. Oxygen can also be used as the oxidizing agent. If a 6 percent hydrogen peroxide solution is used as oxidizing agent, the weight ratio of hair coloring composition and developer composition is 5:1 to 1:5, but preferably 1:1. In general, the hair dyeing composition comprising primary intermediate(s) and coupler(s), including at least one of the compounds of formula (1), is prepared and then, at the time of use, the oxidizing agents, such as H₂O₂, contained in a developer composition is admixed therewith until an essentially homogenous composition is obtained, which is applied shortly after preparation to the hair to be dyed and permitted to remain in contact with the hair for a dyeing effective amount of time. The mixture of the oxidizing agent and the dye composition of the invention (i.e., the hair dye product composition) is allowed to act on the hair for about 2 to about 60 minutes, preferably about 15 to 45, especially about 30 minutes, at about 15 to 50° C., the hair is rinsed with water, and dried. If necessary, it is washed with a shampoo and rinsed, e.g., with water or a weakly acidic solution, such as a citric acid or tartaric acid solution. Subsequently the hair is dried. Optionally, a separate conditioning product may also be provided.

[0095] Together the hair dye composition of the present invention comprising the hair dye primary intermediate (1) and the developer composition comprising the oxidizing agent form a system for dyeing hair.

[0096] This system may be provided as a kit comprising in a single package separate containers of the hair dye composition, the developer, the optional conditioner or other hair treatment product, and instructions for use.

[0097] Especially useful primary intermediates of formula (1) of this invention will provide hair coloring compositions having outstanding color fastness, especially light fastness, fastness to washing and fastness to rubbing.

[0098] Dyeing Example 1

[0099] The following composition shown in Table 1 can be used for dyeing Piedmont hair. 100 g of the dyeing composition is mixed with 100 g 20 volume hydrogen peroxide. The resulting mixture is applied to the hair and permitted to remain in contact with the hair for 30 minutes. The dyed hair is then shampooed, rinsed with water and dried. The ranges of ingredients set out in Table 1 are illustrative of useful concentrations of the recited materials in a hair dye product. TABLE 1 Composition for Dyeing Hair Ingredients Range (wt %) Weight (%) Cocamidopropyl betaine  0-25 17.00 Polyquaternium-22 0-7  5.00 Monoethanolamine¹  0-15  2.00 Oleic Acid  2-22  0.75 Citric Acid 0-3  0.10 28% Ammonium hydroxide¹  0-15  5.00 Behentrimonium chloride 1-5  0.50 Sodium sulfite 0-1  0.10 EDTA 0-1  0.10 Erythorbic acid 0-1  0.40 Ethoxydiglycol  1-10  3.50 C11-15 Pareth-9 (Tergitol 15-S-9) 0.5-5    1.00 C12-15 Pareth-3 (Neodol 25-3) 0.25-5    0.50 Isopropanol  2-10  4.00 Propylene glycol  1-12  2.00 p-phenylenediamine 0-5 1 mmole N,N-Bis(hydroxyethyl)-p-phenylene 0-5 1 mmole diamine 3-Methyl-p-aminophenol 0-5 1 mmole p-Aminophenol 0-5 1 mmole Primary Intermediate of this invention 0.5-5   4 mmoles 5-Amino-2-Methyl Phenol² 0-5 3 mmoles 2,4-Diaminophenoxyethanol² 0-5 3 mmoles M-Phenylenediamine² 0-5 1 mmole Water qs to 100.00 qs to 100.00

[0100] Exemplary combinations of hair coloring components employing a novel primary intermediate of formula (1) of this invention are shown in Table 1 and in combinations C1 to C136 in Tables A through H. Reading down the columns in Tables A through H, the Xes demonstrate combinations of dyes that can be formulated according to the present invention. For example, in Combination No. C1 in Column 4 of Table A, a primary intermediate compound of formula (1) of this invention (Row 1 of Table A) where R₁ and R₂ are as defined before, can be combined with 2-amino-phenol. Especially preferred as the primary intermediate compounds of formula (1) in such combinations as identified in Table 1 and in Tables A through H are the following:

[0101] 4-amino-2-(1-phenylamino-ethyl)-phenol;

[0102] 4-amino-2-(1-piperidin-1-yl-ethyl)-phenol;

[0103] 4-amino-2-[1-(pyridin-3-yl-amino)-ethyl]-phenol;

[0104] 4-amino-2-)1-benzylamino-ethyl)-phenol;

[0105] 4-amino-2-[1-(4-methoxy)-phenylamino-ethyl]-phenol;

[0106] 4-amino-2-(1-amino-ethyl)-phenol;

[0107] 4-amino-2-(1-dimethylamino-ethyl)-phenol;

[0108] 4-amono-2-(1-morpholin-4-yl-ethyl)-phenol;

[0109] 4-amino-2-[1-(4-methoxy)-benzylamino-ethyl]-phenol;

[0110] 4-amino-2-(1-methylamino-ethyl)-phenol; and

[0111] 4-amino-2-[1-(2-hydroxyethylamino)-ethyl]-phenol. TABLE A Dye Combinations Structure IUPAC Name Name C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11

X X X X X X X X X X X

2-Methyl-benzene-1,4- diamine p-Toluene-diamine

Benzene-1,4-diamine p-Phenylene-diamine

2-[(4-Amino-phenyl)-(2- hydroxy-ethyl)-amino]- ethanol N,N-Bis(2-hydroxyethyl)- p-phenylene-diamine

1-(2,5-Diamino-phenyl)- ethanol 1-Hydroxyethyl-p- phenylenediamine

4-Amino-3-methyl- phenol 3-Methyl-p-aminophenol

2-Amino-phenol o-Aminophenol X X

Benzene-1,3-diol Resorcinol X X X

2-Methyl-benzene-1,3- diol 2-Methyl-resorcinol X X

Naphthalen-1-ol 1-Naphthol X

2-Methyl-naphthalen-1- ol 2-Methyl-1-naphthol X

2-(2,4-Diamino- phenoxy)-ethanol 2,4-Diamino- phenoxyethanol X

Benzene-1,3-diamine m-Phenylenediamine X

3-Amino-phenol m-Aminophenol X

5-Amino-2-methyl- phenol 2-Hydroxy-4- aminotoluene X

2-(4,5-Diamino-pyrazol- 1-yl)-ethanol 1-Hydroxyethyl-4,5- diamino-pyrazole

[0112] TABLE B Dye Combinations Structure C12 C13 C14 C15 C16 C17 C18 C19 C20

X X X X X X X X X

X X X

X

X X X X X X X

X

X

X

X

X

X

X

Structure C21 C22 C23 C24 C25 C26 C27 C28 C29

X X X X X X X X X

X X X X X X X X X

X

X X X

X

X X

X

X

X

X

X

[0113] TABLE C Dye Combinations Structure C30 C31 C32 C33 C34 C35 C36 C37 C38

X X X X X X X X X

X X X X X

X X X X

X

X X X X X X

X

X

X

X

X

X

X

Structure C39 C40 C41 C42 C43 C44 C45 C46 C47

X X X X X X X X X

X X X X X X X X X

X

X X X X

X

X

X X

X

X

X

X

[0114] TABLE D Dye Combinations Structure C48 C49 C50 C51 C52 C53 C54 C55 C56

X X X X X X X X X

X X X X

X X X X X

X

X X X X X

X

X

X

X

X

X

X

Structure C57 C58 C59 C60 C61 C62 C63 C64 C65

X X X X X X X X X

X X X X X X X X X

X

X X X X X

X

X

X

X X

X

X

X

[0115] TABLE E Dye Combinations Structure C66 C67 C68 C69 C70 C71 C72 C73 C74

X X X X X X X X X

X X X X X X

X X X

X

X X X X

X

X

X

X

X

X

X

X X X X X X Structure C75 C76 C77 C78 C79 C80 C81 C82 C83

X X X X X X X X X

X X X

X

X X X X X X

X

X

X

X

X

X

X

X X X X X X X X X

[0116] TABLE F Dye Combinations Structure C84 C85 C86 C87 C88 C89 C90 C91 C92

X X X X X X X X X

X X X X X X X

X

X X X

X

X

X

X

X

X

X

X X X X X X X X X Structure C93 C94 C95 C96 C97 C98 C99 C100 C101

X X X X X X X X X

X X

X X X X X X X

X

X

X

X

X

X

X

X

X

X X X X X X X X X

[0117] TABLE G Dye Combinations Structure C102 C103 C104 C105 C106 C107 C108 C109 C110

X X X X X X X X X

X X

X X X X X X X

X

X

X

X

X

X

X

X

X

X X X X X X X x x Structure C111 C112 C113 C114 C115 C116 C117 C118 C119

X X X X X X X X X

X X X X X X X

X X

X

X X X X X X X

X

X

X

X

X

X X

X

x x x x x x x x x

[0118] TABLE H Dye Combinations Structure C120 C121 C122 C123 C124 C125 C126 C127 C128

X X X X X X X X X

X

X X X X X X X X

X

X X X X X X X X X

X

X

X

X

X

X

X X

x x x x x x x x x Structure C129 C130 C131 C132 C133 C134 C135 C136

X X X X X X X X

X X X X X X X X

X

X X X X X X X X

X

X

X

X

X

X

X

x x x x x x x x

[0119] With the foregoing description of the invention, those skilled in the art will appreciate that modifications may be made to the invention without departing from the spirit thereof. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described. 

We claim:
 1. A compound of formula (1):

wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atoms, C₁ to C₅ alkyl, C₁ to C₅ mono or dihydroxyalkyl, phenyl or benzyl optionally substituted with a hydroxyl, amino or C₁ to C₃ alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are attached form a C₃ to C₆ saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms.
 2. A compound of claim 1 wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atom, a C₁ to C₃ alkyl group, phenyl or benzyl optionally substituted with an alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a piperazine, piperidine, imidazole, or morpholine ring.
 3. A compound of claim 2 wherein R₁ is hydrogen and R₂ is phenyl.
 4. A compound of claim 2 wherein R₁ and R₂ together with the nitrogen atom to which they are bound form a piperidine ring.
 5. A compound of claim 2 wherein R₁ and R₂ together with the nitrogen atom to which they are bound form a morpholine ring.
 6. A compound of claim 2 wherein R₁ and R₂ are both methyl.
 7. A process for the preparation of a compound of formula (1) of claim 1 comprising (a) reductively aminating a compound of formula (2):

with a reagent of the formula R₁R₂NH and a reducing agent to produce a compound of formula (3)

and (b) subjecting the compound of formula (3) to acidic hydrolysis to produce a compound of formula (1)

wherein R₁ and R₂ are as defined in claim
 1. 8. A process according to claim 7 wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atom, a C₁ to C₃ alkyl group, phenyl or benzyl optionally substituted with an alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a piperazine, piperidine, imidazole, or morpholine ring.
 9. A process according to claim 7 wherein R₁ is hydrogen and R₂ is phenyl.
 10. A process according to claim 7 wherein R₁ and R₂ together with the nitrogen atom to which they are bound form a piperidine ring.
 11. A hair dye product comprising a hair dyeing composition containing at least one primary intermediate and at least one coupler and a developer composition containing one or more oxidizing agents, the hair dyeing composition containing a primary intermediate comprising a compound of formula (1):

wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atoms, C₁ to C₅ alkyl, C₁ to C₅ mono or dihydroxyalkyl, phenyl or benzyl optionally substituted with a hydroxyl, amino or C₁ to C₃ alkoxy group, or R₁ and R² together with the nitrogen atom to which they are attached form a C₃ to C₆ saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms.
 12. A hair dye product according to claim 11 wherein the hair dyeing composition additionally comprises a primary intermediate selected from the group consisting of: 2-methyl-benzene-1,4-diamine, benzene-1,4-diamine, 2-(2,5-diamino-phenyl)-ethanol, 1-(2,5-diamino-phenyl)-ethanol, 2-[(4-amino-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, 4-amino-phenol, 4-methylamino-phenol, 4-amino-3-methyl-phenol, 1-(5-amino-2-hydroxy-phenyl)-ethane-1,2-diol, 2-amino-phenol, 2-amino-5-methyl-phenol, 2-amino-6-methyl-phenol, N-(4-amino-3-hydroxy-phenyl)-acetamide, pyrimidine-2,4,5,6-tetramine, 2-(4,5-diamino-1H-pyrazol-1-yl)ethanol, 1-(4-methylbenzyl)-1H-pyrazole-4,5-diamine, and 1-(benzyl)-1H-pyrazole-4,5-diamine.
 13. A hair dye product according to claim 11 wherein the coupler present in the hair dyeing composition is selected from the group consisting of: benzene-1,3-diol, 4-chlorobenzene-1,3-diol, naphthalen-1-ol, 2-methyl-naphthalen-1-ol, 2-methyl-benzene-1,3-diol, 2-(2,4-diamino-phenoxy)-ethanol, 2-(3-amino-4-methoxy-phenylamino)-ethanol, 2-[2,4-diamino-5-(2-hydroxy-ethoxy)-phenoxy]-ethanol, and 3-(2,4-diamino-phenoxy)-propan-1-ol, 3-amino-phenol, 5-amino-2-methyl-phenol, 5-(2-hydroxy-ethylamino)-2-methyl-phenol, 3-amino-2-methyl-phenol, 3,4-dihydro-2H-1,4-benzoxazin-6-ol, 4-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, 1H-indol-6-ol, and 2-aminopyridin-3-ol.
 14. A hair dye product according to claim 13 wherein the hair dyeing composition additionally comprises a primary intermediate selected from the group consisting of: 2-methyl-benzene-1,4-diamine, benzene-1,4-diamine, 2-(2,5-diamino-phenyl)-ethanol, 1-(2,5-diamino-phenyl)-ethanol, 2-[(4-amino-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, 4-amino-phenol, 4-methylamino-phenol, 4-amino-3-methyl-phenol, 1-(5-amino-2-hydroxy-phenyl)-ethane-1,2-diol, 2-amino-phenol, 2-amino-5-methyl-phenol, 2-amino-6-methyl-phenol, N-(4-amino-3-hydroxy-phenyl)-acetamide, pyrimidine-2,4, 5,6-tetramine, 2-(4,5-diamino-1H-pyrazol-1-yl)ethanol, 1-(4-methylbenzyl)-1H-pyrazole-4,5-diamine, and 1-(benzyl)-1H-pyrazole-4,5-diamine.
 15. A hair dye product according to claim 11 wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atom, a C₁ to C₃ alkyl group, phenyl or benzyl optionally substituted with an alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a piperazine, piperidine, imidazole, or morpholine ring.
 16. In a hair dyeing system wherein at least one primary intermediate is reacted with at least one coupler in the presence of an oxidizing agent to produce an oxidative hair dye, the improvement wherein the at least one primary intermediate comprises a compound of the formula (1):

wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atoms, C₁ to C₅ alkyl, C₁ to C₅ mono or dihydroxyalkyl, phenyl or benzyl optionally substituted with a hydroxyl, amino or C₁ to C₃ alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are attached form a C₃ to C₆ saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms.
 17. A hair dyeing composition for dyeing human hair comprising, in a suitable carrier or vehicle, a dyeing effective amount of: (a) at least one coupler, and (b) at least one primary intermediate comprising a compound of the formula (1):

wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atoms, C₁ to C₅ alkyl, C₁ to C₅ mono or dihydroxyalkyl, phenyl or benzyl optionally substituted with a hydroxyl, amino or C₁ to C₃ alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are attached form a C₃ to C₆ saturated or unsaturated ring optionally containing in the ring one or more additional hetero atoms selected from O, S and N atoms.
 18. A hair coloring composition of claim 17 wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atom, a C₁ to C₃ alkyl group, phenyl or benzyl optionally substituted with an alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a piperazine, piperidine, imidazole, pyridine, or morpholine ring.
 19. A hair dyeing composition according to claim 17 additionally comprising a primary intermediate selected from the group consisting of: 2-methyl-benzene-1,4-diamine, benzene-1,4-diamine, 2-(2,5-diamino-phenyl)-ethanol, 1-(2,5-diamino-phenyl)-ethanol, 2-[(4-amino-phenyl)-(2-hydroxy-ethyl)-amino]-ethanol, 4-amino-phenol, 4-methylamino-phenol, 4-amino-3-methyl-phenol, 1-(5-amino-2-hydroxy-phenyl)-ethane-1,2-diol, 2-amino-phenol, 2-amino-5-methyl-phenol, 2-amino-6-methyl-phenol, N-(4-amino-3-hydroxy-phenyl)-acetamide, pyrimidine-2,4,5,6-tetramine, 2-(4,5-diamino-1H-pyrazol-1-yl)ethanol, 1-(4-methylbenzyl)-1H-pyrazole-4,5-diamine, and 1-(benzyl)-1H-pyrazole-4,5-diamine.
 20. A hair dyeing composition according to claim 19 wherein the at least one coupler is selected from the group consisting of: benzene-1,3-diol, 4-chlorobenzene-1,3-diol, naphthalen-1-ol, 2-methyl-naphthalen-1-ol, 2-methyl-benzene-1,3-diol, 2-(2,4-diamino-phenoxy)-ethanol, 2-(3-amino-4-methoxy-phenylamino)-ethanol, 2-[2,4-diamino-5-(2-hydroxy-ethoxy)-phenoxy]-ethanol, and 3-(2,4-diamino-phenoxy)-propan-1-ol, 3-amino-phenol, 5-amino-2-methyl-1phenol, 5-(2-hydroxy-ethylamino)-2-methyl-phenol, 3-amino-2-methyl-phenol, 3,4-dihydro-2H-1,4-benzoxazin-6-ol, 4-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, 1H-indol-6-ol, and 2-aminopyridin-3-ol.
 21. A hair dyeing composition according to claim 17 wherein the at least one coupler is selected from the group consisting of: benzene-1,3-diol, 4-chlorobenzene-1,3-diol, naphthalen-1-ol, 2-methyl-naphthalen-1-ol, 2-methyl-benzene-1,3-diol, 2-(2,4-diamino-phenoxy)-ethanol, 2-(3-amino-4-methoxy-phenylamino)-ethanol, 2-[2,4-diamino-5-(2-hydroxy-ethoxy)-phenoxy]-ethanol, and 3-(2,4-diamino-phenoxy)-propan-1-ol, 3-amino-phenol, 5-amino-2-methyl-phenol, 5-(2-hydroxy-ethylamino)-2-methyl-phenol, 3-amino-2-methyl-phenol, 3,4-dihydro-2H-1,4-benzoxazin-6-ol, 4-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, methyl-phenol, 1H-indol-6-ol, and 2-aminopyridin-3-ol.
 22. A hair dyeing composition of claim 17 wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atom, a C₁ to C₃ alkyl group, phenyl or benzyl optionally substituted with an alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a piperazine, piperidine, imidazole, pyridine, or morpholine ring.
 23. A process for dyeing hair comprising forming a hair dye product composition by mixing a developer composition and a hair dyeing composition as defined in claim 17, applying to the hair an amount of the hair dye product composition effective to dye the hair, permitting the hair dye product composition to contact the hair for period of time effective to dye the hair, and removing the hair dye product composition from the hair.
 24. A process according to claim 23 wherein R₁ and R₂ are each individually selected from the group consisting of hydrogen atom, a C₁ to C₃ alkyl group, phenyl or benzyl optionally substituted with an alkoxy group, or R₁ and R₂ together with the nitrogen atom to which they are bound form a piperazine, piperidine, imidazole, or morpholine ring. 